1. Field of the Invention
The present invention generally relates to computer systems and, more particularly, to a pointer device, commonly referred to as a mouse, which is used to control a visual pointer on a display of a computer system.
2. Description of the Related Art
A computer system includes many components, such as the central processing unit (or processor); temporary memory for storing program instructions (like random access memory, or RAM); a permanent storage device (such as a hard disk); and a variety of user interface devices, such as a video display, a keyboard, and a pointing device which controls the movement of a graphical pointer on the display. The graphical pointer is used to select certain areas on the screen, such as words in a text-only display or icons in a more complicated graphical user interface (GUI). An area is selected by placing the graphical pointer over the area (i.e., moving the physical pointing device) and then clicking one or more buttons on the pointing device. Other operations can be performed using the graphical pointer besides simple selection, such as "drag and drop" operations.
The pointing device, often referred to as a "mouse," can come in a variety of physical embodiments. The most familiar design is a hand-held controller having a ball therein which extends partially through a hole in the bottom of the unit, so that the unit can be pushed along a flat surface to cause the ball to roll. Transducers within the unit (such as optical transducers) convert the motion of the ball to electrical signals which are transmitted to the processor or to a controller circuit connected to the processor, which, in turn, decodes those signals to determine how the graphical pointer on the display should be manipulated. Other physical embodiments of pointer devices include electrically sensitive pads, joysticks, and joystick-type actuators, a track ball, etc.
A typical mouse is shown in FIG. 1. Mouse 10 is generally comprised of a body 12 having one or more buttons 14, 16, and a roller ball (not visible in FIG. 1) which partially extends through a hole in the underside of body 12. When body 12 is pushed along a relatively flat surface, the roller ball's movements are sensed and appropriate signals are generated and sent to the computer system via wire 18 (transmission can also be wireless, e.g., radio wave or infrared). The signals are typically sensed by an input/output (I/O) controller which is connected to the computer's central processing unit (CPU); the CPU interprets the signals and sends appropriate data to a display adapter which then causes "movement" of the graphical pointer on the display. Mouse movement, measured in units called "mickies," is a constant of the mouse itself. A certain mouse movement distance always results in the same number of mickies being reported to the host system. Software commonly allows the user to adjust the sensitivity (i.e., speed) of the graphical pointer, such that it may be slowed down to allow finer movements or sped up to move the pointer more quickly across the display screen, by programming different pointer movement rates for a certain number of mickies. A similar software adjustment can provide for "acceleration" of the graphical pointer, i.e., moving the graphical pointer even more quickly, based on the length of time that the mouse is being moved along a given direction.
The body of a conventional mouse is usually sized to fit comfortably in an adult hand, which is often a problem, for example, if a child with a small hand is using it, or if an adult with a particularly large hand is using it. This problem can make using the device especially difficult for people with trauma disorders such as repetitive stress injuries (e.g., carpal tunnel syndrome), due to the repetitive nature of manipulation of the mouse in movement and button clicking. Gripping a mouse for extended periods of time is common in computer-related jobs and creates a high level of exertion and fatigue. The importance of proper hand and wrist support is discussed further in U.S. Pat. No. 5,340,067.
In addition to the size of the mouse, its shape also can vary. Early mice were basically rectangular, but recent mice include more curved and profiled designs to provide improved support. In addition to symmetric designs, asymmetric designs may be provided for left- and right-handed users. Each of these units are, however, independent, complete pointing devices which must be interchanged with any pointing device already connected to the computer system. For example, if a right-handed user wanted to switch out a left-handed mouse, the latter device would first have to be unplugged from the computer port and then a right-handed mouse plugged in. This swapping procedure can be troublesome if, for example, the computer system has a large housing or chassis with the mouse port in the back, which might be pushed up against a wall or otherwise not particularly accessible. Also, many computer systems have to be re-initialized (booted) when a different mouse is connected to the system, in order to properly register the mouse software driver. These difficulties make it practically impossible for a group of individuals, such as in a family, to use a wide variety of mice with different sizes or shapes. It would, therefore, be desirable to devise a method of providing a wide variety of mouse shapes and sizes without requiring swapping out the mice. It would be further advantageous if different mice designs could be provided in a low-cost manner.